This invention relates to a medical balloon for use in expanding or seating a medical device such as a stent at a desired bodily location. More specifically, this invention relates to a balloon having protrusions thereon which are constructed and arranged to prevent unwanted movement of an expandable medical device such as a stent, stent-graft, graft or vena cava filter mounted thereon.
Expandable, implantable medical devices such as stents are utilized in a number of medical procedures and situations as are stent delivery assemblies. As such their structure and function are well known. A stent is a generally cylindrical prosthesis introduced via a catheter into a lumen of a body vessel in a configuration having a generally reduced diameter and then expanded to the diameter of the vessel. In its expanded configuration, the stent supports and reinforces the vessel walls while maintaining the vessel in an open, unobstructed condition.
Self-expanding, inflation assisted expandable and inflation expandable stents are well known and widely available in a variety of designs and configurations. Inflation expandable and inflation assisted expandable stents are expanded via outward radial pressure such as that provided by a balloon disposed underneath the stent during inflation of the balloon.
In using such stents and other expandable, implantable medical devices, it is necessary to position the expandable, implantable medical device in a precise location within a bodily lumen. This goal is rendered more difficult because slippage may occur during insertion of the expandable, implantable medical device through a guide catheter or during deployment of the expandable, implantable medical device. To facilitate the proper positioning of an expandable, implantable medical device, it is desirable to prevent any unwanted relative movement between any of the expandable, implantable medical device, the balloon, the catheter and the interior of the vessel.
One approach to limiting slippage in a catheter assembly involves providing a balloon whose body has a lubricating portion and a non-lubricating portion. This approach is directed in particular to the so-called `watermelon seed` problem wherein a balloon which is too lubricious shoots forward on inflation.
Approaches to reducing slippage of the balloon relative to the vessel involve the use of a balloon with spikes, felt, or other shaped surface thereon which frictionally engages the interior of the vessel.
These approaches address balloon slippage in a lesion. They do not address the problem of slippage of an expandable, implantable medical device relative to a balloon.
The issue of slippage of an expandable, implantable medical device relative to a balloon has been dealt with in several different ways including by varying the coefficient of friction of the exposed portion of a balloon between the uninflated and inflated states of the balloon. Another approach involves providing a balloon with enlarged ends and a middle section of reduced diameter to retain a stent. Yet another approach involves encapsulated a stent with a balloon. Other approaches are nonballoon based, providing stent retention devices that extends from the catheter and engage the stent.
Patents, publications and applications of interest include U.S. Pat. No. 5,503,631 to Onishi, U.S. Pat. No. 5,545,132 to Fagan, U.S. Pat. No. 5,746,745 to Abele et al., U.S. Pat. No. 5,423,745 to Todd et al., U.S. Pat. No. 5,487,730 to Marcadis et al., U.S. Pat. No. 5,250,070 to Parodi, U.S. Pat. No. 4,927,412 to Menasche, U.S. Pat. No. 5,836,965 to Jendersee et al., WO 94/23787 and copending and commonly assigned U.S. patent application Ser. No. 09/141209.
It is a goal of the present invention to provide a medical device delivery system with improved medical device deployment accuracy which prevents slippage of the expandable, implantable medical device during delivery of the device to a desired bodily location and during deployment of the device to facilitate the positioning of the expandable, implantable medical device. In particular, it is a goal of the present invention to provide a stent delivery system having a balloon with protrusions extending therefrom to prevent the stent from substantially moving longitudinally relative to the balloon until the stent has been deployed.
All US patents and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.